/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.catalina.tribes.transport.nio;

import org.apache.catalina.tribes.*;
import org.apache.catalina.tribes.io.ChannelData;
import org.apache.catalina.tribes.io.XByteBuffer;
import org.apache.catalina.tribes.transport.AbstractSender;
import org.apache.catalina.tribes.transport.MultiPointSender;
import org.apache.catalina.tribes.transport.SenderState;
import org.apache.catalina.tribes.util.Logs;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

import java.io.IOException;
import java.net.UnknownHostException;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;

/**
 * <p>Title: </p>
 * <p>
 * <p>Description: </p>
 * <p>
 * <p>Company: </p>
 *
 * @author not attributable
 * @version 1.0
 */
public class ParallelNioSender extends AbstractSender implements MultiPointSender {

	private static final Log log = LogFactory.getLog(ParallelNioSender.class);
	protected long selectTimeout = 5000; //default 5 seconds, same as send timeout
	protected Selector selector;
	protected HashMap<Member, NioSender> nioSenders =
			new HashMap<Member, NioSender>();

	public ParallelNioSender() throws IOException {
		synchronized (Selector.class) {
			// Selector.open() isn't thread safe
			// http://bugs.sun.com/view_bug.do?bug_id=6427854
			// Affects 1.6.0_29, fixed in 1.7.0_01
			selector = Selector.open();
		}
		setConnected(true);
	}

	@Override
	public synchronized void sendMessage(Member[] destination, ChannelMessage msg) throws ChannelException {
		long start = System.currentTimeMillis();
		this.setUdpBased((msg.getOptions() & Channel.SEND_OPTIONS_UDP) == Channel.SEND_OPTIONS_UDP);
		byte[] data = XByteBuffer.createDataPackage((ChannelData) msg);
		NioSender[] senders = setupForSend(destination);
		connect(senders);
		setData(senders, data);

		int remaining = senders.length;
		ChannelException cx = null;
		try {
			//loop until complete, an error happens, or we timeout
			long delta = System.currentTimeMillis() - start;
			boolean waitForAck = (Channel.SEND_OPTIONS_USE_ACK & msg.getOptions()) == Channel.SEND_OPTIONS_USE_ACK;
			while ((remaining > 0) && (delta < getTimeout())) {
				try {
					remaining -= doLoop(selectTimeout, getMaxRetryAttempts(), waitForAck, msg);
				} catch (Exception x) {
					if (log.isTraceEnabled()) log.trace("Error sending message", x);
					int faulty = (cx == null) ? 0 : cx.getFaultyMembers().length;
					if (cx == null) {
						if (x instanceof ChannelException) cx = (ChannelException) x;
						else cx = new ChannelException("Parallel NIO send failed.", x);
					} else {
						if (x instanceof ChannelException)
							cx.addFaultyMember(((ChannelException) x).getFaultyMembers());
					}
					//count down the remaining on an error
					if (faulty < cx.getFaultyMembers().length) remaining -= (cx.getFaultyMembers().length - faulty);
				}
				//bail out if all remaining senders are failing
				if (cx != null && cx.getFaultyMembers().length == remaining) throw cx;
				delta = System.currentTimeMillis() - start;
			}
			if (remaining > 0) {
				//timeout has occurred
				ChannelException cxtimeout = new ChannelException("Operation has timed out(" + getTimeout() + " ms.).");
				if (cx == null) cx = new ChannelException("Operation has timed out(" + getTimeout() + " ms.).");
				for (int i = 0; i < senders.length; i++) {
					if (!senders[i].isComplete()) cx.addFaultyMember(senders[i].getDestination(), cxtimeout);
				}
				throw cx;
			} else if (cx != null) {
				//there was an error
				throw cx;
			}
		} catch (Exception x) {
			try {
				this.disconnect();
			} catch (Exception e) {/*Ignore*/}
			if (x instanceof ChannelException) throw (ChannelException) x;
			else throw new ChannelException(x);
		}

	}

	private int doLoop(long selectTimeOut, int maxAttempts, boolean waitForAck, ChannelMessage msg) throws IOException, ChannelException {
		int completed = 0;
		int selectedKeys = selector.select(selectTimeOut);

		if (selectedKeys == 0) {
			return 0;
		}

		Iterator<SelectionKey> it = selector.selectedKeys().iterator();
		while (it.hasNext()) {
			SelectionKey sk = it.next();
			it.remove();
			int readyOps = sk.readyOps();
			sk.interestOps(sk.interestOps() & ~readyOps);
			NioSender sender = (NioSender) sk.attachment();
			try {
				if (sender.process(sk, waitForAck)) {
					completed++;
					sender.setComplete(true);
					if (Logs.MESSAGES.isTraceEnabled()) {
						Logs.MESSAGES.trace("ParallelNioSender - Sent msg:" + new UniqueId(msg.getUniqueId()) + " at " + new java.sql.Timestamp(System.currentTimeMillis()) + " to " + sender.getDestination().getName());
					}
					SenderState.getSenderState(sender.getDestination()).setReady();
				}//end if
			} catch (Exception x) {
				if (log.isTraceEnabled()) {
					log.trace("Error while processing send to " + sender.getDestination().getName(), x);
				}
				SenderState state = SenderState.getSenderState(sender.getDestination());
				int attempt = sender.getAttempt() + 1;
				boolean retry = (sender.getAttempt() <= maxAttempts && maxAttempts > 0);
				synchronized (state) {

					//sk.cancel();
					if (state.isSuspect()) state.setFailing();
					if (state.isReady()) {
						state.setSuspect();
						if (retry)
							log.warn("Member send is failing for:" + sender.getDestination().getName() + " ; Setting to suspect and retrying.");
						else
							log.warn("Member send is failing for:" + sender.getDestination().getName() + " ; Setting to suspect.", x);
					}
				}
				if (!isConnected()) {
					log.warn("Not retrying send for:" + sender.getDestination().getName() + "; Sender is disconnected.");
					ChannelException cx = new ChannelException("Send failed, and sender is disconnected. Not retrying.", x);
					cx.addFaultyMember(sender.getDestination(), x);
					throw cx;
				}

				byte[] data = sender.getMessage();
				if (retry) {
					try {
						sender.disconnect();
						sender.connect();
						sender.setAttempt(attempt);
						sender.setMessage(data);
					} catch (Exception ignore) {
						state.setFailing();
					}
				} else {
					ChannelException cx = new ChannelException("Send failed, attempt:" + sender.getAttempt() + " max:" + maxAttempts, x);
					cx.addFaultyMember(sender.getDestination(), x);
					throw cx;
				}//end if
			}
		}
		return completed;

	}

	private void connect(NioSender[] senders) throws ChannelException {
		ChannelException x = null;
		for (int i = 0; i < senders.length; i++) {
			try {
				senders[i].connect();
			} catch (IOException io) {
				if (x == null) x = new ChannelException(io);
				x.addFaultyMember(senders[i].getDestination(), io);
			}
		}
		if (x != null) throw x;
	}

	private void setData(NioSender[] senders, byte[] data) throws ChannelException {
		ChannelException x = null;
		for (int i = 0; i < senders.length; i++) {
			try {
				senders[i].setMessage(data);
			} catch (IOException io) {
				if (x == null) x = new ChannelException(io);
				x.addFaultyMember(senders[i].getDestination(), io);
			}
		}
		if (x != null) throw x;
	}

	private NioSender[] setupForSend(Member[] destination) throws ChannelException {
		ChannelException cx = null;
		NioSender[] result = new NioSender[destination.length];
		for (int i = 0; i < destination.length; i++) {
			NioSender sender = nioSenders.get(destination[i]);
			try {

				if (sender == null) {
					sender = new NioSender();
					AbstractSender.transferProperties(this, sender);
					nioSenders.put(destination[i], sender);
				}
				sender.reset();
				sender.setDestination(destination[i]);
				sender.setSelector(selector);
				sender.setUdpBased(isUdpBased());
				result[i] = sender;
			} catch (UnknownHostException x) {
				if (cx == null) cx = new ChannelException("Unable to setup NioSender.", x);
				cx.addFaultyMember(destination[i], x);
			}
		}
		if (cx != null) throw cx;
		else return result;
	}

	@Override
	public void connect() {
		//do nothing, we connect on demand
		setConnected(true);
	}

	private synchronized void close() throws ChannelException {
		ChannelException x = null;
		Object[] members = nioSenders.keySet().toArray();
		for (int i = 0; i < members.length; i++) {
			Member mbr = (Member) members[i];
			try {
				NioSender sender = nioSenders.get(mbr);
				sender.disconnect();
			} catch (Exception e) {
				if (x == null) x = new ChannelException(e);
				x.addFaultyMember(mbr, e);
			}
			nioSenders.remove(mbr);
		}
		if (x != null) throw x;
	}

	@Override
	public void add(Member member) {
		// NOOP
	}

	@Override
	public void remove(Member member) {
		//disconnect senders
		NioSender sender = nioSenders.remove(member);
		if (sender != null) sender.disconnect();
	}

	@Override
	public synchronized void disconnect() {
		setConnected(false);
		try {
			close();
		} catch (Exception x) {/*Ignore*/}
	}

	@Override
	public void finalize() throws Throwable {
		try {
			disconnect();
		} catch (Exception e) {/*Ignore*/}
		try {
			selector.close();
		} catch (Exception e) {
			if (log.isDebugEnabled()) {
				log.debug("Failed to close selector", e);
			}
		}
		super.finalize();
	}

	@Override
	public boolean keepalive() {
		boolean result = false;
		for (Iterator<Entry<Member, NioSender>> i = nioSenders.entrySet().iterator(); i.hasNext(); ) {
			Map.Entry<Member, NioSender> entry = i.next();
			NioSender sender = entry.getValue();
			if (sender.keepalive()) {
				//nioSenders.remove(entry.getKey());
				i.remove();
				result = true;
			} else {
				try {
					sender.read(null);
				} catch (IOException x) {
					sender.disconnect();
					sender.reset();
					//nioSenders.remove(entry.getKey());
					i.remove();
					result = true;
				} catch (Exception x) {
					log.warn("Error during keepalive test for sender:" + sender, x);
				}
			}
		}
		//clean up any cancelled keys
		if (result) try {
			selector.selectNow();
		} catch (Exception e) {/*Ignore*/}
		return result;
	}

}